The present application is the national stage under 35 U.S.C. 371 of PCT/IB99/00459, filed Mar. 18, 1999.
The present invention relates to an axial flow fan equipped with blades inclined in the plane of rotation of the fan.
The fan disclosed by the present invention has diverse applications, for example, to move air through a heat exchanger or radiator in the cooling system of a motor vehicle or similar engine, or to move air through a heat exchanger in the heating system of the interior compartment of a vehicle. In addition, the fan disclosed by the present invention can be used to move air in the fixed air conditioning or heating installations of buildings.
Fans of this kind have to satisfy various different requirements, including low noise, high efficiency, dimensional compactness and good values of head (pressure) and delivery.
Patent EP-0 553 598 B, in the name of the same Applicant as the present, discloses a fan whose blades have a constant chord length along their entire length. In addition, the leading and trailing edges of the blades form two curves which, if projected onto the plane of rotation of the fan, are two circular arcs. Fans made in accordance with this patent achieve good results in terms of efficiency and low noise but their ability to achieve high head or pressure values is limited mainly because of their small axial dimensions.
The need to achieve high head values has become an increasingly important requirement on account of the thermal units in modern automobiles which include two or more exchangers arranged in seriesxe2x80x94for example, the condenser of the air conditioning system, the radiator of the cooling system and the heat exchanger for the air supply of turbo enginesxe2x80x94or on account of radiators that have become thicker to compensate for the smaller frontal dimensions.
The aim of the present invention is to solve the problem of head or pressure of the above mentioned fans and to further improve them in terms of efficiency and low noise.
The problem is solved by the characteristics described in the independent claim. The dependent claims refer to preferred, advantageous embodiments of the invention.